The present invention relates to a distance measuring apparatus and a distance measuring method, and a passive style distance measuring apparatus and a distance measuring method which are adopted in a camera, a video camera or the like.
Conventionally, in the case where scenes are photographed against the background of a reverse light scene or a night scene with a camera provided with a passive style distance measuring apparatus, an integration operation is conducted by taking a high luminance portion and a light source at the background as a reference.
Consequently, there is a problem in that the background is focused in place of a person who is a main subject so that a person who is the main subject cannot be obtained in an appropriate state.
In order to solve such a disadvantage, for example, Jpn. Pat. Appln. KOKAI Publication No. 5-264887 discloses a technique for conducting an integration operation by detecting reverse light based on light measurement data and distance measurement sensor data, setting in a central portion of a photographing screen a monitor screen for monitoring subject luminance information used for integration control in the state of reverse light, and taking a region where integration speed is the slowest out of a plurality of monitors set in the central portion of the photographing screen or set in advance as a reference.
Furthermore, Jpn. Pat. Appln. KOKAI Publication No. 7-199039 discloses a technique characterized by providing a night scene mode for the night scene photography, judging as to whether auxiliary light is required at the time of a night scene mode, and emitting auxiliary light in the case of low luminance.
However, in the technique disclosed in Jpn. Pat. Appln. KOKAI Publication No. 5-264887, in the case where a high luminance portion at the background is a dot-like reflection light from a high reflection object, and in the case where the main subject such as a person or the like is present at the position other than the center of the photographing screen, the reverse light cannot be detected and furthermore, a signal associated with the main subject is saturated so that a main subject cannot be sufficiently obtained.
Furthermore, in the technique disclosed in Jpn. Pat. Appln. KOKAI Publication No. 7-199039, auxiliary light is not emitted in the case where the light source of the night scene is bright, and the light quantity of auxiliary light is not sufficient in the case where auxiliary light is emitted with the result that no effect is generated.
An object of the present invention is to provide a distance measuring apparatus and a distance measuring method of a camera which is capable of measuring a distance of a main subject with certitude irrespective of a high luminance portion at the background.
In order to attain an object, according to a first aspect, there is provided a distance measuring apparatus comprising:
a sensor for photoelectrically converting a subject image to output a subject image signal corresponding to a luminance distribution;
a monitor region setting portion for setting a monitor region at the time of integration of the sensor;
a distance measuring calculation portion for calculating a distance measurement in correspondence to a region including the monitor region set with the monitor region setting portion; and
a detection portion for detecting a region having a low luminance and a low contrast based on the subject image signal;
wherein the monitor region setting portion sets as a second monitor the low luminance and low contrast region detected with the detection portion region out of a first monitor region set at the first time, and
the sensor conducts the first and the second integration in correspondence to the first and the second monitor regions set with the monitor region setting portion.
Furthermore, according to a second aspect of the present invention, there is provided a distance measuring apparatus comprising:
a sensor for photoelectrically converting a subject image to output a subject image signal corresponding to a luminance distribution;
a monitor region setting portion for setting a monitor region at the time of integration by the sensor;
a sensor data reading portion for reading sensor data at the time of integration by the sensor;
a detection portion for detecting a maximum value out of the sensor data read with the sensor data reading portion;
a calculation region setting portion for setting a region including the monitor region set with the monitor region setting portion as the calculation region;
a comparison portion for comparing the maximum value of the sensor data detected with the detection portion with a predetermined value; and
a judgment portion for judging whether or not a low luminance and low contrast portion is present in the sensor data read with the sensor data reading portion in the case where the comparison portion obtains a comparison result showing that the maximum value of the sensor data is larger than the predetermined value;
wherein the monitor region setting portion sets as a second monitor region the low luminance and low contrast portion out of the first monitor region which is set at the first time in the case where the judgment portion judges the low luminance and low contrast portion is present in the sensor data,
the sensor conducts the first and the second integration corresponding to the first and the second monitor regions set with the monitor region setting portion.
Furthermore, according to a third aspect of the present invention, there is provided a distance measuring method using a distance measuring apparatus for measuring a distance based on sensor data obtained by the integration control of a sensor, the method comprising the steps of:
conducting a first integration with a monitor region for the first integration, and a senor sensitivity for the first integration;
conducting a first calculation based on the first sensor data obtained with the first integration;
detecting a low luminance and low contrast region based on the first sensor data;
setting the low luminance and low contrast region detected in the detection as a monitor for the second integration to conduct the second integration with the monitor region for the second integration and the sensor sensitivity for the second integration;
conducting a second calculation based on the second sensor data obtained with the second integration; and
selecting desired data from the calculation data calculated in the first and the second calculation.
Furthermore, according to a fourth aspect of the present invention, there is provided a distance measuring method using a distance measuring apparatus for determining a subject distance based on the sensor data obtained by the integration control of the sensor, the method comprising the steps of:
conducting a first integration with a monitor region for the first integration, and a senor sensitivity for the first integration;
calculating subject distance data through the first calculation based on the first sensor data obtained from the first integration;
detecting a low luminance and low contrast region based on the first sensor data;
setting the low luminance and low contrast region detected in the detection as a monitor region for the second integration to conduct a second integration with the monitor region for this second integration and the sensor sensitivity for the second integration;
calculating the subject distance data with the second calculation based on the second sensor data obtained in the second integration; and
selecting desired data from the subject distance data calculated with the first and the second calculation as distance measuring data.
Furthermore, according to a fifth aspect, there is provided a distance measuring apparatus comprising:
a sensor for photoelectrically converting a subject image to output a subject image signal corresponding to a luminance distribution;
an integration region setting portion for setting the integration region of the sensor;
a distance measuring calculation portion for calculating the distance measurement corresponding to a region including an integration region set with the integration region setting portion; and
a detection portion for detecting a low luminance and low contrast region based on the subject image signal output from the sensor;
wherein the integration region setting portion sets as a second integration region the low luminance and low contrast region detected with the detection portion out of the first integration region set at the first time; and
the sensor conducts the first and the second integration in correspondence to the first and the second integration region set with the integration region setting portion.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.